Best ways to tag a epitope?

Dear Netters,
I am trying to tag either hemagglutinin or myc epitope to the C-terminal
of my-favorite-gene (MFG), so that I could easily isolate the protein Mfg
with antibody.
I have read a paper where the author tagged three tandem repeats of HA to
immediately downstream of C-terminus, and she got a clear band when
immunoblotted.
My questions are:
1. Is it better to have any number of tandem repeats than to have just
single copy of an epitope when I tag my MFG? If so, what would be a good
method to tag multiple copies? I wondered PCR or in vitro mutagenesis,
but PCR with about 100-base primer seemed unrealistic, and for in vitro
mutagenesis, insertions are (as my knowledge goes) good for the maximum
number of around 30 bases.
2. When I tag MFG, is it alright to tag to the immdediate downstream of
the C-terminus? Shouldn't there be a spacer peptide sequence?
I would appreciate any advice for this.
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* Namjin Chung * *
* Program in Molecular Cancer Biology * Email: nc1 at acpub.duke.edu *
* Duke University Medical Center, Box 3345 * Voice: +1 (919) 684-2363 *
* Durham, NC 27710 * Fax : +1 (919) 681-8253 *
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